xserver-xorg-video-all vs. -1.0 distinction breaks on upgrades to -2

[Josip Rodin <joy@debbugs.entuzijast.net>]

Hi,

I have xserver-xorg-video-nv installed, because that's the only xorg video
driver that I need. I don't have all the other driver packages installed,
because there's unnecessary.

The etch->lenny upgrade nevertheless says:

The following NEW packages will be installed:
[...]
  xserver-xorg-video-all xserver-xorg-video-apm xserver-xorg-video-ark
  xserver-xorg-video-ati xserver-xorg-video-chips xserver-xorg-video-cirrus
  xserver-xorg-video-cyrix xserver-xorg-video-dummy xserver-xorg-video-fbdev
  xserver-xorg-video-glint xserver-xorg-video-i128 xserver-xorg-video-intel
  xserver-xorg-video-mach64 xserver-xorg-video-mga
  xserver-xorg-video-neomagic
  xserver-xorg-video-openchrome xserver-xorg-video-r128
  xserver-xorg-video-radeon xserver-xorg-video-radeonhd
  xserver-xorg-video-rendition xserver-xorg-video-s3
  xserver-xorg-video-s3virge xserver-xorg-video-savage
  xserver-xorg-video-siliconmotion xserver-xorg-video-sis
  xserver-xorg-video-sisusb xserver-xorg-video-tdfx xserver-xorg-video-tga
  xserver-xorg-video-trident xserver-xorg-video-tseng xserver-xorg-video-v4l
  xserver-xorg-video-vesa xserver-xorg-video-vga xserver-xorg-video-vmware
  xserver-xorg-video-voodoo xulrunner-1.9
The following packages will be upgraded:
[...]
  xserver-xorg xserver-xorg-core xserver-xorg-input-evdev
  xserver-xorg-input-kbd xserver-xorg-input-mouse xserver-xorg-video-nv
[...]

This is bad because:

Package: xserver-xorg
Version: 1:7.3+15
Depends: xserver-xorg-core (>= 2:1.4-3), xserver-xorg-video-all | xserver-xorg-video-2, [...]

xserver-xorg-video-nv used to provide the xserver-xorg-video-1.0 virtual
package, and now the new version provides the xserver-xorg-video-2 virtual
package. But apt isn't catching on to the idea - it's ignoring the fact
that it can obtain xserver-xorg-video-2 simply by upgrading
xserver-xorg-video-nv. Instead it is parsing the dependency list as if it's
in a vacuum, seeing that xserver-xorg-video-2 isn't there, and therefore
installing xserver-xorg-video-all.

In a simple A | B dependency, package A clearly takes precedence, that's
what the rules say. But that is oriented towards the new installs.
On upgrades, if B is obtained a) from an already installed package, just
a new version of it b) at a visibly smaller cost -- then that should be
taken into consideration.

As a workaround, I'd just purge xserver-xorg and be done with it.
But xserver-xorg-core depends on it for some reason. The reason seems
to be http://bugs.debian.org/392295 Surely this could have been fixed
by putting that part of code into the xserver-xorg-core package instead
of creating a dependency which is circular?

(The same behaviour seems to apply to both apt-get and aptitude.)

-- 
     2. That which causes joy or happiness.